Return bool in ray_triangle

It only returns booleans, so it doesn't make sense for this to be a
float.

include/intersections.h

@@ -22,7 +22,7 @@ namespace intersections {
         return false;
     }
 
-    inline float ray_triangle(
+    inline bool ray_triangle(
         const Ray ray,
         const glm::vec3 v0,
         const glm::vec3 v1,